124 THOMAS SAY FOUNDATION 



Alloperla pilosa, new species. 



(Plate 20, Bgs. 7, 8, 9.) 



Length to tip of wings, male, 11-13 mm. ; expanse, male, 

 18-21 mm. ; length to tip of wings, female, 12-14 mm. ; ex- 

 panse, female, 20-23 mm. 



General color pale yellow. 



Head very little wider than prothorax, pale yellow; 

 hind ocelli about as close to eyes as to each other; anten- 

 nae yellow, infuscated towards the tip. 



Prothorax transversely oval, wider than long, uniform- 

 ly yellow, somewhat rugose. Legs yellow. Wings yellow- 

 ish hyaline, veins yellowish. 



Abdomen yellow with a broad, median, dorsal stripe. 

 Cerci yellow. 



Male. Tenth abdominal tergite deeply cleft ; supra-anal 

 lobe retractile, flattened dorso-ventrally ; when fully ex- 

 panded it shows a median brown chitinized rod sur- 

 rounded by a membranous sheath to within a short dis- 

 tance of the tip; subanal lobes small, unmodified; ninth 

 abdominal sternite produced and truncate behind. Ninth 

 and tenth tergites with long hairs. 



Female. Subgenital plate of eighth sternite broad at 

 the base and then somewhat narrowed and triangularly 

 produced so that the tip normally reaches almost en- 

 tirely across the ninth sternite. 



Distribution. — Holotype male, allotype female, Boulder, 

 Colo. (G. S. Dodds, in Cornell University Collection). 



Paratypes, three males and one female, same locality ; 

 one male, one female, Aug. 27, 1914, Platte Canon, Colo. 

 (Oslar). 



Alloperla serrata, new species. 



(Plate 20, figs. 12, 13.) 



Length to tip of wings, male, 9-9.5 mm. ; expanse, male, 

 16-17 mm. ; length to tip of wings, female, 11 mm. ; ex- 

 panse, female, 18 mm. 



General color greenish yellow with greenish wings. 



Head a little wider than prothorax, greenish yellow ; 

 ocelli surrounded by a dark ring, more prominent in the 

 hind ocelli ; hind ocelli about as close to eyes as to each 

 other; antennae yellow at base, infuscated towards the 

 tip. 



Prothorax wider than long, almost transversely oval, 

 the angles very broadly rounded ; greenish yellow ; sur- 

 face somewhat rugose. Legs yellow, wings greenish hy- 

 aline, veins greenish. 



Abdomen yellowish. Cerci yellowish. 



